Cylindrical hairspring form



' Dec. 28, 1948.

, w. o. BENNETT, JR 2,457,631

CYLINDRICAL HAIRSPRING FORM Filed. Sept. 22, 1943 2 FIG; 1

FIG.? F|G.8 FIG.9 FIG. IO FIG ll FIG.I2

2o 21 FIG 2| INVENTOR. WILLIAM 0. BENNETT JR.

i BY

Patented Dec. 28, 1948 2,457,631 cYm-NninoAn HAIESPRISTG *FtiitM- William Ogle Bennett, J12, Lancaster TOWIIShip Lancaster County, Pa., assignor to- Hamilton- Watch Company, LancastenPa. Application September 22, 19213; seriarno=s503$9s similar timepieces.

The obiiect "of the p resent invention isto providea fermon whichan untreated wire can be wound andf-r-oni which the heattreated wire may be removed without'inany-way bending. or stressing the eoilsofthe' treated spring";-

I-ri' high grade marine chron'ometers and timepicesof -a"-sirnilar"natiir= where there i is need fora' very unusiial-degi'eeof accuracy, the slightest bend or strain whichcauses internal stresses "in" the-metal will aflf ot the timing; particularly wherrd-r'r' the metal ot the -=hairsprin'g. This -spring'-i-s generally made: m the form of a fiat spiral for most timepieces but for the more accurate instruments such as chronometers it has be enifoun'd' advantageous to make the'hairspring in the form of a cylinder. In makingca cylindrical hairspring' it isnecessary.- that each end be inturned to reach the position of 'the balance staff and balance cock to which they are fastened;

Asf 'hairsp'i'ings are made by winding untreated wire-- on a form; heat treating the wire while 'on the'ior-m, and removing-the wire' irom the form it became necessary to provid a form which a cylindrical hairspr-ing-with its-inti-irned ends could berernoved' without many-way straining the treated wire. ltisthe-pur-pos 'of the p'resent invention" to -provide an apparatus upcn which the] cylindrical shaped hairs'pring formed- I with inturnd end couldbefastened} heat treated and removed Without bending or distorting any part of the spring.

It is a further object of the invention to pro duce a spring which requires no cold working.

It is a further object of the present invention to provide a form which may be used repeatedly.

It is a further object of the present invention to provide a form made up of a number of sections which interfitted together provide the complete form and which may be removed separately without distorting the finished product.

It is a still further object of the present invention to provide a form which insures the correct curves for the ends of the hairspring.

The invention is illustrated in the accompanying drawing in which:

Fig. 1 is a front elevation of the assembled form.

Fig. 2 is an end view of the form.

Fig. 3 is a perspective showing the removal of the sections of the form from the completed spring.

Fig. 4 is a view of the alignment pin.

Fig. 5 is a view of the arbor.

3Claims. (o1; 263 25 Fig. fi-isaa view of! the-endicap.

r Figs through 2B*are views of the several sec tions, making up the form.

Fig? 21 Lisa-view of the wedge pin.

. ln thefdrawirlgsarr-arbor l provided-with an annular 1 shoulder 2;. central section 3; a threaded section 4* supports seriesiof discs -which,.-w-hen assinhled;- providea form' '5 having a helical guideway '6 for'thereception of-a spring I. l

The-form :S'is made un er-section's 8 9, In; -I I, I2; I3; 115; IS} IT, 18,:119; 20 and-2|- all of Which are' formed withaa' centnal hole 22 to receive the central: section B nfthearbcr I. All-ofthefdiscs except the'twof end. discs T-and' 2 I areiormed with? an: aligning"holed: -and.-a"threaded opening 24.: The'idisc" sectibnsfiinlflgulj"; H," It; lfS- -and--20-arealso fornied' with a ho'l"td'=rceiv.e a" wedge pin 2-5. A'capznutfifi'firinly holds all' of thesediscs on th'e'central sectioned 'of the arbor l In assembling-the form 5 the end of the arborl ig' clamped'inwa vice with the' secti'onfl abutting the shoulderi2-recivessection 9i-the cut-out portion' zrnttmg thefendsection' 8. The disc'section ti] is now 'applied' t-ot the center section 3,*the holes 23 being aligned and the pin 28 inserted in' holes 23. In turn, each of the sedtions 'are mounted oirthecentrar section'fi,the cOrrect angular position? being-determined by 'th'e' respective rela tions of the'hol'i? in.th successivefiiscs; The end-section 2t is-"fitted a depression 'ir'i-the disc ZU simiIar to'de'pressidn 2lfin thedisc 91and th'e' capi nut r26 screwed fi'rmiyrim place: The-form is then ready to receive the soft wire used to form the hairspring.

The form 5 is removed from the vice inserted in a chuck which is not shown as it forms no part of the invention other than to provide a convenient means for turning the form. Turning of the form 5 wraps the wire 1 around the form following the spiral 6, the initial holding of the spring wire I being made by fitting the wire in the groove 33 formed between the end section 8 and the cut out portion 21 of section 9, the wire being wedged against the edge 29 by the Wedging i pin 25 in the hole 30. A pin 3| mounted at the point where the wire makes a sharp bend prevents any buckling or backing up of the wire at the time the wedge pin is driven in. This, of course, is not important in initially securing the wire but after the spring has been wound the importance of preventing any slack in the wound Wire While securing the loose end cannot be stressed too strongly, After having been wound on the form 5, the loose end of the spring is se-. cured in a manner similar to the first fastening I by a wedge pin 25 used against the side of disc 2! ina manner similar to that previously described. The wound wire is then given the necessary heat treatment, cooled and ready for removal of the form 5 from the completed spring. It is necessary that the removal of the form be 1 accomplished without in any way cold working either by forcing or bending the spring wire,

although a small movement of the spring which does not produce a permanent distortion will not afiect its timekeeping qualities. 1 In the removal of thespring the form 5 is j 1 again held in a vice, the cap nut'4 unscrewed and the central arbor I removed. With the removal of the arbor the openings 23'are exposed and the aligning pin 28 may be driven out. The device is then removed from a vice by means of a jack 3 I screw 32, having a threaded end which fits the I. f threaded opening 24, the discs are separated and removed one at a time. The relation of the successive discs are such that no two successive threaded holes are aligned and the tool 32 hav- 1 ing a threaded portion greaterthan the thickness of any one disc will, on being threaded into the opening of any disc, bear against the metal of the sucessive disc and gently separate the successive 1 1 discs one at a time." It isthen possible to spread the coils of. the finished spring slightly so that 3 these thin discs'may be passed between the coils I i as shown in Fig. 3, as it is impossible to slide the spring 01f the form or the form from the spring 3 because of the preformed inturned ends. In this 1 way the spring I is removed from the form 5 by having the form removed from the spring a section at a time. It is thereby possible to produce i sisting of inner discs andend discs, said inner What is claimed is:

1. A form for holding cylindrica1 hairsprings 1 with preformed inturned ends during heat treat- I ment comprising an arbor, a series of discs condisc being substantially identical and said end disc being formed'to receive .the ends of the spring in a predetermined configuration, discs being adapted to be placed upon the arbor, means for aligning said discs in predetermined position, a

spiral guideway formed by the periphery of said discs to receive a wire and means for anchoring the inturned ends of said wire at each end of the assembled discs.

r 2. A-iOrm for holding cylindrical .hairsprings With preformed inturned ends during heat treatment comprising an arbor, a series of discs formed with a central opening receivable on said arbor,

saidseries of discs including two end disc sections. and a number of substantially identical intermediate' sections, the periphery of the intermediate sections forming a spiral guideway to receive a wire, the two end sections formed to receive the endsof the wire in-a predetermined manner, means for holding the discs in close relation and means for anchoring the ends of said wire.

3. A form for holding cylindrical hairsprings with preformed inturned ends during heat treatment'comprisingan, arbonfan annular shoulder, on said arbor, a series of discs each formed with a central opening-an aligning opening and a threaded opening positioned 'onrsaid arbor each of said discs having: ayperlpheral groove and together forming .a cylinder having an externalspiral guideway,- to; receive a; wire, analignment pin passing through;. the aligning holes and-properly positioning said discs, wedge pins securing the ends of said wire anda jack screwfitting the threaded opening of thediscs for removing said discs sucessively without; distortion of the wire subsequent to spring forming process.

VTILLIAM-, QGLE BENNETT, JR.

- E EB N- SC ED v I The following references are oprecord inthe file of this patent:

UNITED, STATES PA'rENTs I Date Number Nam d...

25,294 Weimer Aug. 30, 1859 109,826 Kline Dec. 6,1870 477,525 Ferrell June 21, 1892 1,215,775 Campbell Feb. 13,1917 "1,483,985 Price Feb. 19, 1924 1,928,727 T Johnson Oct, 3,1933 2,142,865 Zabe1' Jan. 3, 1939 2,236,206 Becker, Mar. 25, 1941 2,236,907 I-Ioffsommer Apr. 1,1941 

